1. Field of the Invention
This invention relates to an output section of microwave tubes such as klystrons and traveling-wave tubes.
2. Background of the Prior Art
One type of structure for the output section of microwave tubes such as klystrons is to have a rectangular waveguide joined to the end of a coaxial line which is connected to the output cavity. A vacuum-tight aperture made of a ceramic dielectric is set up in part of the waveguide. Alternatively, a dielectric air-tight wall may be set up partway along the coaxial line section {U.S. Pat. No. 3,254,263 (Nelson) and Japanese Patent Laid open No. 56-42097}. In the former case, however, there is the problem that after the tube evacuation, it is almost impossible to adjust the coupling characteristics between the coaxial line and the waveguide especially for high power level. In the latter case, also, it is extremely difficult to make a structure which adequately resists multipactor phenomena and thermal stress on the dielectric air-tight wall. For these reasons, existing structures have the limitation that they cannot handle high power levels.